Ladder



May z, 1944.

F. KIDD ET AL I LADDER Filed AprilA 1, 194s Patented May 2, 1944 UNITED STATES sans LADDER Frederick Kidd and Thomas Dargue Kidd, Stcckton-on-Tees, England Application April 1, 1943, Serial No. 481,404 In Great Britain February 12, 1942 (Cl. 22S-d3) 4 Claims.

This invention relates to ladders, the object being to provide improvements therein.

A ladder constructed in accordance with this invention is characterised in that the sides are curved longitudinally and the upper ends of each side are connected to their respective lower ends by a tie member. The ladder may be made of metal. The ladder Will form, in side elevation, a bowstring girder, the sides of the ladder providing the arc and the tie members the chord. Two ladders may be associated to form an extension ladder and/or a step ladder.

Referring to the accompanying drawing- Fig. 1 is a side elevation of one form of ladder constructed in accordance with the invention; and

Fig. 2 is a front elevation.

Figs. 3 and 4 are side elevations of a two-section ladder forming, respectively, an extension ladder and a step ladder.

Fig. 5 is an enlarged section on line V-V of Fig. 3.

Figs. 6, 7 and 8 are enlarged fragmentary views of details of the construction shown in Figs. 3 and 4.

Referring to Figs. l and 2 the two sides or rails a, a1 are formed of steel angle bars with one flange b of one rail a in lateral alignment with a ange b1 of the other rail al, the two said anges being directed towards each other, the other flange-s c, c1 of each rail being parallel to each other. rungs d may be secured to the rails a, a1 in any suitable manner, for example, they may be formed of steel tubes, the ends being flattened and secured to the inwardly directed flanges b, b1 of the rails by welding, riveting or other suitable means, preierably being secured to the faces of said flanges inside the angles. The rails a, al are arcuately curved longitudinally as shown in Fig. l. Each rail is provided with a tie member e, which may be an iron or steel rod, the ends of the said tie member being secured by welding or other suitable means to the said rail at or near the ends thereof. The ladder, in side elevation, will resemble a bowstring girder, the tie members or chords e being at the rear of the ladder.

A ladder constructed as hereinbeiore described will be rigid, as, when a person climbs the ladder his weight will tend to straighten the rails and will thereby put the tie members e in tension. It

will also be comparatively light as the side rails a, a1 may be made of comparatively light angle bars; for example, in a ladder approximately eleven feet long the rails may be constructed of angle bars having a section one inch by one inch by one-eighth inch, whilst the tie members may be round iron rods of three-sixteenths inch section.

The sides or rails, the rungs, and the tie members may be of any suitable metal and section. For examples, the sides or rails may be of T, H, channel, tubular or solid round section, the rungs may be of solid round, T, H, channel or angle section, and the tie members may be constructed of steel tubing -or of stranded steel wire, in which latter case the ends of the tie members may be secured to the rails by shackles.

Two ladders or sections of the type shown in Figs. 1 and 2 may be associated to form either an extending ladder as shownin Fig. 3 or a step ladder as shown in Fig. 4. The upper end of one section f, Figs. 3, 5 and 6, is provided with brackets g, y and a transverse rail h to form a guide through which the side rails of another section i may pass. The lower end of the Section i, Figs. 3 and `8, is provided with pivoted hooks lc adapted to engage the rungs of the section J; thereby, the two sections may form an extension ladder, being locked together in a required position by the hooks k engaging selected rungs of the section f.

The ladder shown in Fig. 3 may be further adapted, by forming the lower ends of the rails of the section i as S -hooks m, to form a step ladder, as shown in Figs. 4 and 8. The two sections are fully extended in relation to each other and then the section i is allowed to fall over, the inner portions of hooks m engaging the rail h to provide a fulcrum, Figs. 4 and '7 the outer ends of the hooks m will engage the under face of the top rung of the section f.

The brackets gg may be secured to the section f in any suitable manner, either permanently or temporarily; when temporarily secured they may be removed when desired so that the two sections f and i may be separated to be used as separate ladders.

What we claim and desire to secure by Letters Patent is:

l. A ladder in which the sides are curved longitudinally and the upper ends of the sides are connected to their respective lower ends by tie members in tension which are free between their ends.

2. A ladder comprising two sections, the sides of each section are curved longitudinally and the upper ends of the sides are connected to their respective lower ends by tie members which are free between their ends, a guide member is secured to the upper end of one section and is adapted to engage the other section and the lower end oi' the other section is provided with pivoted hooks adapted to engage the rungs of the one section to form an extension ladder.

3. A ladder according to claim 2 wherein the guide member comprises brackets secured to the one section of the ladder and a transverse rail adapted to embrace the sides of the other section of the ladder.

4. A ladder according to claim 2 wherein the guide member comprises brackets secured to the one section of the ladder and a transverse rail adapted to embrace the sides of the other section of the ladder and wherein the lower ends of the sides of the guided section form S-hooks adapted to engage the guide member and the top rung of the other section so that the two sections may form a step ladder.

FREDERICK KIDD.

THOMAS DARGUE KIDD. 

